| Summary: | 碩士 === 國立中興大學 === 電機工程學系 === 90 === The capacity of transmission system increase due to the widely use of broadband applications by customers. In order to enhance transmission systems capacity, DWDM utilize one pair of optical fiber to transmit multi-wavelength signals. WDM with OA (Optical Amplifier) could offer long distance, high capacity transmission system. Either the ″All Optical Network″ in the future or the ″Synchronization Digital Hierarchy″ nowadays will be the trend of fiber communication development.
In conventional serial coding systems, coding-induced
parity-check bits are added to the encoded data sequences so that the system bit rate is inevitably increased. In practical lightwave systems, the change of system bit rate is generally unacceptable. FEC for SONET or SDH put parity-check bits in unassigned overheads of the frame. System bit rate thereby is unchanged. The results show that the performance of a dispersion-limited lightwave system is improved drastically. However, as parity-check bits are put on some specific overheads, the required signal processing in the encoder/decoder becomes complicated, resulting in limiting its operating speed. Extending to high-capacity WDM systems with many high-speed wavelength channels, numerous encoder/decoders will be necessary.
Taking advantage of the parallel nature of WDM systems, putting parity-check bits in additional wavelength channels was proposed by [4] and [7]. In [7] based on product codes, it required only one encoder/decoder and two additional wavelength channels to correct one error in any all of wavelength channels. The implementation of the scheme is straightforward and simple since the codeword can be encoded, transmitted and decoded all in parallel. Therefore, the resulting coding scheme is simple and efficient.
In this thesis we presented a modified interchannel WDM coding system with four parity-check wavelength channels which will provide a double-error correction capability to the systems. Correcting burst-errors scheme in any all of wavelength channels and adjacent wavelength channels are also proposed. The performance with other coding schemes are analyzed and compared. Finally, the generalization of interchannel coding in WDM lightwave systems to arbitrary error-correction capability has also been given.
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